Carbon monoxide poisoning (COP) is one of the most common types of potentially fatal poisoning throughout the world. Hyperbaric oxygen therapy (HBOT) is an effective and quick response modality that clears symptoms and prevents sequelae. HBOT should be administered within 4-6 hours after poisoning. The aim of this study was to contribute COP treatment protocols by retrospectively examining the results of COP cases who were administered HBOT according to clinical and laboratory findings at the Emergency Department.